We recently bought a 1993 Ford 250 truck. It runs great but will not pass emmissions and the check engine light comes on sometimes and then goes off. We put new sparrk plugs and wires on but it still will not pass emmissions!What could be our problem with it? any ideas?
You need to pull the codes from the computer to determine what’s causing the Check Engine light to come on. Here’s a link showing how this is done and what the code definitions are. http://www.extreme-check-engine-light-codes.com/Ford%20OBD1%20Decoder.htm
Tester
If the check light comes on then the computer is storing error codes.
For that year you might have to go to the Ford dealer or a knowledgeable independent to read them.
The code(s) will say what system to check out, not what part to change.
note: I had this reply sitting in a tab for a couple of hours, didn’t see Testers reply.
Is the truck failing the emission testing because the CEL is ‘on’ or because of high emissions measured from the tail pipe? If the tail pipe emissions are high, give us the moiety i.e. HC, CO, or Nox; the measured levels at which RPM; and the limit values.
Help us help you.